Question

A stone is dropped from the top of a tower 500 m high into a pond of water at the base of the tower. When is the splash heard at the top? (Given, g= 10ms^-2 and speed of sound = 340ms^-1)

Answer 1

Time after which splash is heard = Time taken by the stone to reach the pond + Time taken by the splash sound to reach the top of tower.
(i) For the time taken by the stone to reach the pond.
Here u = 0 (∵ stone is dropped from rest)
From equation of motion against gravity.

(ii) Time taken by splash sound to reach the top of lower

∴ Time after which splash is heard = 10 + 1.47 = 11.47 S.